Ilkka Leinonen

Multi-sensor plant imaging: Towards the development of a stress-catalogue

Agricultural production is limited by a wide range of abiotic (e.g. drought, waterlogging) and biotic (pests, diseases and weeds) stresses. The impact of these stresses can be minimized by appropriate management actions such as irrigation or chemical pesticide application. However, further optimization requires the ability to diagnose and quantify the different stresses at an early stage. Particularly valuable information of plant stress responses is provided by plant imaging, i.e. non‐contact sensing with spatial resolving power: (i) thermal imaging, detecting changes in transpiration rate and (ii) fluorescence imaging monitoring alterations in photosynthesis and other physiological processes. These can be supplemented by conventional video imagery for study of growth. An efficient early warning system would need to discriminate between different stressors. Given the wide range of sensors, and the association of specific plant physiological responses with changes at particular wavelengths, this goal seems within reach. This is based on the organization of the individual sensor results in a matrix that identifies specific signatures for multiple stress types. In this report, we first review the diagnostic effectiveness of different individual imaging techniques and then extend this to the multi‐sensor stress‐identification approach.

Impacts of Climate Change on Cold Hardiness of Conifers

Due to increased anthropogenic emissions into the atmosphere, concentrations of CO2 and other greenhouse gases have been increasing globally during the past decades. Despite realized and planned control measures, this increase is predicted to continue in the future. Due to the accompanying changes in the physical properties of the atmosphere, the air temperature of the globe is predicted to rise dramatically in the future. According to most meteorological scenarios, the increase of the global mean temperature will be 1 to 4.5°C by the year 2100. However, it is also predicted that the level of warming will be more pronounced in the north than in the south and greater during winter than during summer months (IPCC 1996).

Modelling Cold Hardiness Development and Loss in Conifers

The development of cold hardiness in coniferous species is, as in most woody species, under the control of the climatic environment that prevails where the trees are grown. Although there are interspecific differences in the capacity for cold hardening and a wide range of variation exists, it is likely that there is a generic process for the plants to cold harden and deharden. In this chapter we describe the seasonal changes in cold hardiness in conifer species and use this seasonality of hardening and dehardening as a basis to discuss the quantitative aspects of environmental control of the development and loss of cold hardiness. Finally, these quantitative relationships are the bases for development of predictive models of cold hardening and dehardening.

Effects of Climatic Warming on Frost Damage of Scots Pine

The development of frost hardiness and frost damage of Scots pine was described by a dynamic model where the input variables were temperature, photoperiod and the phase of annual development. The model was linked to a forest growth model FINNFOR. Simulations were carried out using generated weather data including climatic warming. During most of the simulated years frost damage increased slightly as a result of climatic warming. Climatic warming also increased the frequency of heavy frost damage. However, the warming may prevent heavy damage in extremely cold winters.